Contact block for oxygen probe The wires used in the thermocouple contact blocks are extension wires. They are separated into type SC(RC), type BC and type WRe3/25(D). They are separately matched with Pt10Rh-Pt (Pt13Rh-Pt) Pt30Rh-Pt6Rh and WRe3-WRe25 expendable thermocouple.